TXsilverado

iTrader: (19)

never dug into a hydro boost system. I have a feeling I know what the issue is, but i'm wondering if some of you guys have seen the same symptoms before.

2002 2500HD with OEM hydro boost system.

basically, if I quickly grab the brakes (not slamming on them), the peddle has a "bounce" to it, then acts normal. literally, the peddle feels like it bounces. it's been doing this for years.

when at a red light, i can foce the peddle to the floor if i want to. it feels normal, and the truck will lock the brakes up if i want to, but the peddle will keep going.

my assumption is it needs a new master cylinder, but like i said...never dealt with hydro boost before.

TXsilverado

iTrader: (19)

maybe brake pedal kick back is a better description. it's a weird feeling to explain.

Atomic

iTrader: (42)

Have you confirmed proper fluid level? I have seen some weird things happen when there is too much or too little fluid.

TXsilverado

iTrader: (19)

fluid is topped off. from some reading, it seems like the answer GM has for this sensation is that it's just how hydroboost works/feels (the kick back feeling, not the peddle going to the floor if I force it.

GMCtrk

iTrader: (27)

Mine actually did the same thing. It was that weird felling after pushing the pedal in just barely. Never made any big deal out of it.

TXsilverado

iTrader: (19)

ok. the kick back is normal and I need to order a new master cylinder. I've always noticed the kick back (had the truck about 3 years now) but was never sure if something was wrong, or if it was normal for hydroboost. it's an odd feeling i cant seem to get used to.

Fullpower

.................................................. .....................No. Pedal kickback is NOT normal.
.
Resurrection:


I have two Tahoes, daily drivers.
2004 was factory equipped with HydroBoost.
'02 was retrofit. Neither rig has anything remotely close to the kickback you are describing.
The two Hydro-Boost Tahoes have totally normal, seemless brake pedal feel, just like every other vehicle on the road. somewhat less pedal effort required than the vacuum models.

Drove a couple old ( 1980-ish) Chevy One-Tons that had the pedal kickback, and BOTH had rusted out rear brake lines, seized rear bleedrs screws, and had 20 year old fluid and ancient, OEM front hoses. It is very highly LIKELY that there is some air in your brake system that is causing your pedal kickback.
ABS systems are difficult to bleed completely. I have had success with repeated brake LOCKUPS on wet grass, or gravel roads to activate ABS system, and then bleeding the resultant air from the calipers./ Repeat as necessary. " It's The AIR in the lines."

wardlws

I've upgraded two trucks from Vacuum to HydroBoost. Neither have a bounce or push back from the pedal. I have felt it before in a Vacuum Boosted system, so I bet it is air in the brake lines. For the pedal hitting the floor, it could be master cylinder isn't sealing.

I had to replace the master cylinder on my '12 Escalade, and it drove me nuts for about an hour of bleeding... not having a Tech II to command the ABS to purge. Finally, I just put it higher up on jack stands, started the engine, and quickly put in drive and then back to neutral while holding the brake. It made a bunch of ABS noises, but after repeating a few times, I was able to bleed all of the air out. Don't put it back into park until the axles stop spinning (if the brakes don't work at all, you can use the parking brake).